Development and Validation of Stability Indicating HPLC Method for Determination of Caffeic Acid, Vitexin and Rosmarinic Acid in Thunbergia laurifolia Leaf Extract, Woottisin, Nanthakarn, Kongkiatpaiboon Sumet, Sukprasert Sophida, and Sathirakul Korbtham , Pharmacognosy Journal, May 2020, Volume 12, Issue 3, p.611-618, (2020)